Mechanisms of mixed umbilical cord blood-derived mesenchymal stem cells inhibiting proliferation and inducing apoptosis of C6 glioma cells in vitro

Abstract

Objective To study the mechanisms of the mixed umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) inhibiting proliferation and inducing apoptosis of C6 glioma cells in vitro. Methods Cysteinyl aspartate-specific protease (Caspase)-8, B cell lymphoma/leukemia-2 associated X protein (bax), B cell lymphoma/leukemia-2 (bcl-2) and Caspase-3 protein expression in C6 cells was analyzed by immunohistochemistry and Western blotting, respectively. Caspase-8, bax, bcl-2 and Caspase-3 mRNA levels were detected by reverse transcriptase-polymerase chain reaction (RT-PCR). Cell cycle was detected by flow cytometry. Apoptosis of C6 cells was examined by Annexin V-propidium iodide (PI) staining and terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL) methods, respectively. Results The mixed UCB-MSCs had a tendency to increase the expression of Caspase-8, bax, Caspase-3 mRNA, and decrease the expression of bcl-2 mRNA. The expression of apoptosis protein and the number of apoptosis cells increased with the increase of the ratio of E/T (E: effect cells namely UCB-MSCs; T: target cells namely C6 cells), showing a proportional dependence relationship; E∶T=(5+ 5)∶1. The relative expression of Caspase-8, bax, bcl-2, and Caspase-3 mRNA in C6 cells was 0.78±0.13, 0.28±0.03, 0.70±0.08, and 0.76±0.12, respectively. When E/T=0∶1, 5∶1, (2.5+ 2.5)∶1, 10∶1, (5+ 5)∶1, the number of apoptosis C6 cells was (2.9±0.6), (3.1±0.5), (14.5±1.8), (14.3±2.2), and (22.8±4.5) cells, respectively. Conclusion After phytohemagglutinin (PHA) stimulation, the mixed UCB-MSCs could inhibit proliferation of C6 cells in vitro, which was related to induction of apoptosis of glioma cells. Key words: Glioma; Umbilical cord blood; Mesenchymal stem cells; Apoptosis; Proliferation